The invention relates to an arrangement for carrying out a method of manufacturing an optically readable disc by forming an optically readable structure in a structure zone on a substrate, the method comprising the application of a replication layer in a deformable phase on a mold having a mold structure, the placement of the substrate on the replication layer, the solidification of the replication layer and its connection to the substrate, and the joint removal of the substrate and the replication layer attached thereto from the mold.
Three U.S. Pat. Nos. 4,670,077, 4,827,469, and 4,911,776 (herewith incorporated by reference) describe a method of the type defined above, and an arrangement and a mold for carrying out the method. The known method can be used, for example, for manufacturing inscribable optical information discs having an optically readable structure comprising servo tracks provided with servo-information. The known method employs a mold mounted on a base. The mold is covered with a radiation-curable transparent lacquer which, after curing, is removed from the mold together with a transparent substrate. In its center the base of the mold has base centering means relative to which the mold structure is centered accurately. Before a substrate is placed on the mould the substrate is provided with central hub means having central disc-centring means to enable the resulting finished information disc to be centered on the drive spindle of a drive arrangement. The intermediate product comprising the substrate with the hub means is centered on the mould base by cooperation of the base-centring means with the disc-centering means. This cooperation is achieved by the use of auxiliary centering means which are brought into contact both with the wall of the centering aperture in the disc hub and with the wall of a central centering recess in the base. Thus, the replication layer is cured in a situation in which the substrate is centered on the mold without clearance. After the intermediate product comprising the substrate and hub with the cured lacquer has been removed from the mold the centering of the disc-centering means relative to the information structure is rigidly maintained. This is because the intermediate product forms an inseparable unit.
The known method is only suited for use with substrates having a central opening and a central hub. This means that it is not suited for discs having a central opening but not a hub, or having a central opening in which a hub is mounted at a later stage. Moreover, the known method is not suited for substrates without a central opening. However, the method described has the advantage that the information structure is centered highly accurately relative to the center of rotation of the substrate. Moreover, this high accuracy can be guaranteed without the need to measure the position of the center of the information structure for every substrate before the hub can be connected to the substrate.